scholarly journals Novell Application of CFD for Rocket Engine Nozzle Optimization

2018 ◽  
Vol 47 (2) ◽  
pp. 131-135
Author(s):  
Csaba Jéger ◽  
Árpád Veress
Keyword(s):  
Simulation Model ◽  
Rocket Engine ◽  
Pressure Ratio ◽  
Geometry Optimization ◽  
Optimization Procedure ◽  
Geometric Optimization ◽  
Nozzle Geometry ◽  
Nozzle Contour ◽  
Nozzle Geometries ◽  
Optimization Loop

Numerical analyses, validation and geometric optimization of a converging-diverging nozzle flows has been established in the present work. The optimal nozzle contour for a given nozzle pressure ratio and length yields the largest obtainable thrust for the conditions and thus minimises the losses. Application of such methods reduces the entry cost to the market, promote innovation and accelerate the development processes. A parametric geometry, numerical mesh and simulation model is constructed first to solve the problem. The simulation model is then validated by using experimental and computational data. The optimizations are completed for conical and bell shaped nozzles also to find the suitable nozzle geometries for the given conditions. Results are in good agreement with existing nozzle flow fields. The optimization loop described and implemented here can be used in the all similar situations and can be the basis of an improved nozzle geometry optimization procedure by means of using a multiphysics system to generate the final model with reduced number sampling phases.

Experimental Improvement of Ejector Performance Through Numerical Optimization of Nozzle Geometry

2013 ◽  
Author(s):  
Navid Sharifi ◽  
Majid Sharifi
Keyword(s):  
Optimization Procedure ◽  
Nozzle Geometry ◽  
Cfd Models ◽  
Steam Ejector ◽  
Nominal Pressure ◽  
Fixed Constant ◽  
Nozzle Geometries ◽  
The One ◽  
Suction Flow ◽  
The Given

Ejectors are widely used in different applications such as refrigeration, propulsion, evacuation and aerospace. They use a pressurized flow as a motive stream to entrain a secondary flow or suction flow. In the current study, a malfunctioning steam ejector is studied experimentally to identify the sources of low compression ratio. This ejector was designed to operate under a motive pressure of 6 bar. However, the required vacuum in the system was not attained unless the pressure of motive steam was increased to 8 bar. The steam ejector was coupled with other unit operating facilities and hence, the ejector replacement was very costly. Therefore, the fastest and the most inexpensive way of improving the device performance was considered as replacing just the primary nozzle and without any further change in ejector’s geometry. To achieve the required vacuum under the available motive pressure (i.e. 6 bar), a CFD–based optimization procedure was performed and different nozzle shapes were numerically investigated. The CFD Models were constrained to a fixed constant throat since the optimized nozzle shall not consume more flow rate than the former one. Ten different nozzle geometries were scrutinized in this numerical simulation and the one, which yields the highest entraining performance under the given boundary condition (i.e. motive flow pressure of 6 bar), was selected as the most optimized nozzle and manufactured. After installing the designed nozzle, an improved entrainment capability was observed and a desired vacuum level was attained under the nominal pressure of 6 bar.

Optimization of Turbofan Propulsion Cycle Using a Genetic Algorithm

2010 ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Genetic Algorithm ◽  
Fuel Consumption ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Optimization Procedure ◽  
Specific Fuel Consumption ◽  
High Mass ◽  
Design Parameters ◽  
Inlet Temperature ◽  
Simplifying Assumptions

This paper presents an evolutionary approach as the optimization framework to design for the optimal performance of a high-bypass unmixed turbofan to match with the power requirements of a commercial aircraft. The parametric analysis had the objective to highlight the effects of the principal design parameters on the propulsive performance in terms of specific fuel consumption and specific thrust. The design optimization procedure based on the genetic algorithm PIKAIA coupled to the developed engine performance analyzer (on-design and off-design) aimed at finding the propulsion cycle parameters minimizing the specific fuel consumption, while meeting the required thrusts in cruise and takeoff and the restrictions of temperatures limits, engine size and weight as well as pollutants emissions. This methodology does not use engine components’ maps and operates on simplifying assumptions which are satisfying the conceptual or early design stages. The predefined requirements and design constraints have resulted in an engine with high mass flow rate, bypass ratio and overall pressure ratio and a moderate turbine inlet temperature. In general, the optimized engine is fairly comparable with available engines of equivalent power range.

scholarly journals Combined Magnetohydrodynamic and Geometric Optimization of a Hypersonic Inlet

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
Kamesh Subbarao ◽  
Jennifer D. Goss
Keyword(s):  
Magnetic Field ◽  
Numerical Optimization ◽  
Splitting Method ◽  
Optimization Procedure ◽  
Geometric Optimization ◽  
Control Parameters ◽  
Flow Solution ◽  
Hypersonic Inlet ◽  
Mass Capture ◽  
The Magnetic Field

This paper considers the numerical optimization of a double ramp scramjet inlet using magnetohydrodynamic (MHD) effects together with inlet ramp angle changes. The parameter being optimized is the mass capture at the throat of the inlet, such that spillage effects for less than design Mach numbers are reduced. The control parameters for the optimization include the MHD effects in conjunction with ramp angle changes. To enhance the MHD effects different ionization scenarios depending upon the alignment of the magnetic field are considered. The flow solution is based on the Advection Upstream Splitting Method (AUSM) that accounts for the MHD source terms as well. A numerical Broyden-Flecher-Goldfarb-Shanno- (BFGS-) based procedure is utilized to optimize the inlet mass capture. Numerical validation results compared to published results in the literature as well as the outcome of the optimization procedure are summarized to illustrate the efficacy of the approach.

An Attempt to Improve the Deposition Efficiency of AI2O3 Coating by HVOF Spraying

2000 ◽  
Author(s):  
Y. Shimizu ◽  
K. Sugiura ◽  
K. Sakaki ◽  
A. Devasanapathi
Keyword(s):  
Hardness Test ◽  
Deposition Efficiency ◽  
Nozzle Geometry ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Dense Microstructure ◽  
Alumina Particles ◽  
Coating Characteristics ◽  
Nozzle Geometries ◽  
Spraying Process

Abstract High Velocity Oxy-Fuel (HVOF) method using propylene as a fuel gas was employed to spray alumina particles. In order to improve the coating characteristics such as the deposition efficiency and the hardness, three HVOF gun nozzles of varying geometry were designed and tested experimentally. The spraying process was also simulated numerically for each of the nozzle geometries to understand their effectiveness in influencing the velocity and temperature of the sprayed particles. The coating was characterized using optical and scanning electron microscopy (SEM), micro-vickers hardness test and X-ray diffractometry (XRD). Results showed that with the use of a convergent and divergent type gun nozzle, similar to that of a Laval nozzle, the extent of melting of the alumina particles could be increased. This was exhibited by an increase in the deposition efficiency to the extent of 45%. However, the sharp changes in the convergent and divergent nozzle geometry, resulted in fusion and agglomeration of alumina particles leading to spitting during the spraying process. The results clearly showed that alumina coatings of excellent hardness in the range of 920-1290 HV, with a relatively dense microstructure could be obtained in HVOF method irrespective of the gun nozzle geometry, provided the spraying parameters are properly controlled.

scholarly journals An efficient multi-factor geometry optimization based on motion analysis and resonance response for hinged double-body floating wave energy converter

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042095015
Author(s):  
Biao Li ◽  
Fangfang Sui ◽  
Bingsong Yang
Keyword(s):  
Motion Analysis ◽  
Wave Energy ◽  
Geometry Optimization ◽  
Geometric Optimization ◽  
Wave Energy Converter ◽  
Geometrical Parameters ◽  
Optimization Strategy ◽  
Energy Converter ◽  
Pitching Motion ◽  
Resonance Response

In the practical engineering applications of multi-body floating wave energy converter (WEC), the traditional geometric optimization is always expensive and time-consuming. This study aim to propose a more efficient geometry optimization strategy with a hinged double-body floating WEC as the study object. The influences of geometric parameters of the buoys on the pitching motion and energy conversion ability are analyzed by numerical simulation. Simulation results show that the resonance state of the pitching motion of the buoys mainly depends on their radius and draft rather than the length; But the length of the buoys, rather than the radius and draft, always has a significant effect on the pitching phase difference of the adjacent buoys. Based on the motion analysis and resonance response, an efficient multi-factor geometry optimization strategy is put forwarded. By the strategy, the sub-optimal and optimal geometrical parameters are solved out quickly at several typical wave conditions of China Seas. The results indicate that the optimal total length of WEC is approximately equal to the wave length. The optimal diameter of buoys is about 25% of the length of buoys. And the optimal draft should attain about 61% of the diameter.

Nozzle Geometry Effect on Twin Jet Flow Characteristics

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Muthuram A ◽  
Thanigaiarasu S ◽  
Rakesh Divvela ◽  
Rathakrishnan Ethirajan
Keyword(s):  
Mach Number ◽  
Flow Characteristics ◽  
Nozzle Geometry ◽  
Ambient Atmosphere ◽  
Free Jets ◽  
Twin Jets ◽  
Equivalent Area ◽  
Nozzle Configuration ◽  
Jet Nozzle ◽  
Nozzle Geometries

AbstractEffect of nozzle geometries on the propagation of twin jet issuing from nozzles with circle-circle, circle-ellipse, circle-triangle, circle-square, circle-hexagon and circle-star geometrical combinations was investigated for Mach numbers 0.2, 0.4, 0.6 and 0.8. In all the cases, both jets in the twin jet had the same Mach number. All the twin jets of this study are free jets, discharged into stagnant ambient atmosphere. The result of the twin jets issuing from circle-circle nozzle is kept as the reference in this study. For all the twin jet nozzles, the inter nozzle spacing; the distance between the nozzle axes (S) was 20 mm and all the nozzles had an equivalent area of 78.5 mm2. Thus for all the cases of the present study, S/D ratio is 2. The results show that the mixing of the combined jet, after the merging point is strongly influenced by the combined effect of the nozzle geometry and jet Mach number. Among the six different twin jet nozzle configuration studied, circle-square combination is found to be the most superior mixing promoter.

scholarly journals Numerical Simulation of Reactive Flows in Overexpanded Supersonic Nozzle with Film Cooling

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Mohamed Sellam ◽  
Amer Chpoun
Keyword(s):  
Film Cooling ◽  
Structural Integrity ◽  
Safety Issue ◽  
Rocket Engine ◽  
Supersonic Nozzle ◽  
Nozzle Geometry ◽  
Nozzle Flow ◽  
Rocket Engines ◽  
Flow Conditions ◽  
Reactive Flows

Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems. These phenomena concern mainly rocket engines which use H2gas (GH2) in the film cooling device, particularly when the nozzle operates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can lead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the rocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are at the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for supersonic reactive flows in a planar nozzle cooled with GH2film. Like the experimental observations, CFD simulations showed their ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms of cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film injection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.

scholarly journals Comparison of Genetic Algorithm and Harmony Search Method for 2D Geometry Optimization.

2018 ◽  
Vol 159 ◽  
pp. 01009 ◽  
Author(s):  
Mohammad Ghozi ◽  
Anik Budiati
Keyword(s):  
Genetic Algorithm ◽  
Harmony Search ◽  
Geometry Optimization ◽  
Steel Structure ◽  
Search Method ◽  
Geometric Optimization ◽  
Computational Time ◽  
Time Required ◽  
Average Computational Time ◽  
Better Than

There are many applications of Genetic Algorithm (GA) and Harmony Search (HS) Method for solving problems in civil engineering design. The question is, still, which method is better for geometry optimization of a steel structure. The purpose of this paper is to compare GA and HS performance for geometric optimization of a steel structure. This problem is solved by optimizing a steel structure using GA and HS and then comparing the structure’s weight as well as the time required for the calculation. In this study, GA produced a structural weight of 2308.00 kg to 2387.00 kg and HS scored 2193.12 kg to 2239.48 kg. The average computational time required by GA is 607 seconds and HS needed 278 seconds. It concludes that HS is faster and better than GA for geometry optimization of a steel structure.

Effect of Nozzle Geometry on the Near-Field Flow Characteristics of High-Pressure Gas Leak Jets

2018 ◽  
Author(s):  
Xiaopeng Li ◽  
Fakun Zhuang ◽  
Rui Zhou ◽  
Yian Wang ◽  
Libo Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Nozzle Exit ◽  
Flow Behavior ◽  
Near Field ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Major Axis ◽  
Minor Axis ◽  
Nozzle Geometry ◽  
Square Jets

Three-dimensional large eddy simulations of high-pressure jets at the same nozzle pressure ratio of 5.60 but issuing from different nozzles are conducted. Four different nozzle geometries, i.e., the circular, elliptic, square, and rectangular nozzles, are used to investigate the effect of the nozzle geometry on the near-field jet flow behavior. A high-resolution, hexahedral, and block-structured grid containing about 31.8 million computational cells is applied. The compressible flow solver, astroFoam, which is developed based on the OpenFOAM C++ library, is used to perform the simulations. The time-averaged near-field shock structures and the mean axial density are compared with the experiment data to validate the fidelity of the LES results, and the reasonable agreement is observed. The results indicate that the remarkable differences exist in the near-field flow structures of the jets. In particular, the circular and square jets correspond to a three-dimensional helical instability mode, while the elliptic and rectangular jets have a two-dimensional lateral instability in their minor axis planes. A subsonic flow zone exists after the Mach disk in the circular and square jets, but is lacking in the elliptic and rectangular jets. The intercepting shocks in the circular jet originate near the nozzle exit, and appear to be circular in cross-section. The intercepting shocks in the square jet originate at the four corners of the nozzle exit at first, and then are observed along the major axis plane some distance downstream of the nozzle exit. However, the formation of the intercepting shock is observed in the major axis planes but is lacking in the minor axis planes for the elliptic and rectangular jets. In addition, the real mass flow rates and discharge coefficients for different jets are computed based on the LES modeling, and their differences are explored.

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